Fiber optic systems have been developed which transmit optical signals at a single wavelength. More recently, however, wavelength division multiplexing (WDM) has been explored for increasing the capacity of existing fiber optic networks. In a WDM system, plural transmitters emit optical signal channels, which are combined onto a single optical fiber, with each channel being assigned a particular wavelength. The optical signal channels are demultiplexed downstream from the transmitters, and converted into electrical signals in corresponding receivers for further processing.
Advances in optical component technologies have increased the channel counts in WDM systems. As a result, high capacity WDM systems carrying in excess of 40 channels or wavelengths are commercially available. With the added capacity, however, comes a need to effectively manage the bandwidth created by current WDM systems. Accordingly, switches have been incorporated into WDM systems to direct optical signals from one fiber. In certain applications, optical channels on one fiber are demutiplexed, converted to electrical signals, which are then used to generate optical signals on different fibers. However, electrical components in these devices are required to perform the optical-to-electrical (O/E) and then electrical-to-optical (E/O) conversion are expensive. Accordingly, all-optical switches have been developed which may cost considerably less than those requiring O/E and E/O conversion.
In an optical switch, optical signals at a particular wavelength are supplied through an input and directed toward an output through various switching mechanisms. The signals input to the switch, however, may not be of equal intensity, and thus, will not have equal intensity when output, in particular, if one channel is supplied from a transmitter located relatively close to the switch while another is located farther away. Moreover, the insertion loss for optical signals input to the switch is often wavelength-dependent. When these signals are supplied to an optical amplifier in a WDM system, power imbalances can occur, whereby certain channels are amplified more than others. After propagating through a chain of such amplifiers, the high power channels absorb most of the amplifier""s energy, while the low power channels experience little if any gain and are practically indiscernible over noise inherently produced in these systems.
Consistent with the present invention, an optical switch is provided that outputs optical signals with substantially uniform intensity levels.
In particular, the optical switch consistent with the present invention includes a plurality of optical input ports, and a plurality of optical output ports. A plurality of mirrors are further included, each of which being configured to direct at least a portion of an optical signal supplied to one of the plurality of optical input ports to a corresponding one of the plurality of optical output ports such that an intensity associated with each of the plurality of optical signals output from the optical switch is substantially the same.